1. Field of the Invention
This invention relates to an improved rotary cutter, and, more particularly, to a rotary cutter which is capable of rounding the corners of a cut sheet when cutting a web into a sheet of a desired length.
2. Description of the Prior Art
As a method for cutting a web into sheets of a desired length, it is well known to use a pivotally moved cutter having an upper blade which is moved pivotally with respect to a stationary lower blade. Improved cutting efficiency can be achieved, however, by the use of a rotary cutter.
The pivotally moved cutter exhibits many disadvantages including a large variation in load in the mechanical portions and a low accuracy in the cutting operation, both of which are due to the pivotal movement of the movable blade.
The rotary cutter, on the other hand, exhibits the capability of continuous cutting of a web at a high cutting speed, as compared with that by the pivotally moved cutter, with a resultant improved cutting capability per unit time. The conventional rotary cutter utilizes a linear contour for each blade, and thus, provides a cut sheet having a linear cut edge. However, in order to provide rounded corners to a sheet cut by such a conventional rotary cutter, the cut sheet must be subjected to a separate punching or rounding step.